/Engine/Plugins/Animation/IKRig/Source/IKRigEditor/Public/RetargetEditor/IKRetargetEditorController.h
Get the retargeter that is running in the viewport (which is a duplicate of the source asset)
[UIKRetargetProcessor](API\Plugins\IKRig\Retargeter\UIKRetargetProcessor) * GetRetargetProcessor() const